Inconsistent motorway emergency features

Smart motorways illustrate the some of the consequences of the UK’s two-system measurement muddle. Ronnie Cohen explains.

So-called smart motorways have recently been in the news. Higher numbers of accidents and near misses have been reported on them compared to regular motorways. Smart motorways are motorways without hard shoulders. They use electronic lane displays and technology to track stationary vehicles to warn other drivers. Many claim that they are less safe than regular motorways and that a hard shoulder could have prevented some accidents and near-misses on smart motorways.

On 12 March 2020, the Secretary of State for Transport published a package of 18 measures to improve safety on smart motorways to address the safety problems with smart motorways (source: I was disappointed to find that all the measures that involved measurements used imperial units. These are inconsistent with the exclusively metric road design and construction and the exclusively metric emergency marker system.

One of the proposed measures includes “reducing the distance between places to stop in an emergency to three quarters of a mile where feasible so that on future schemes motorists should typically reach one every 45 seconds at 60mph. The maximum spacing will be 1 mile”. They are currently 1.5 miles apart. The DfT gives these measurements in miles but the same DfT gives road contractors all specifications in metric units. These metric units include millimetres, metres and kilometres and can be found in the Traffic Signs Manual.

Another measure is “considering a national programme to install more emergency areas where places to stop in an emergency are more than one mile apart”.

The DfT proposes to install “more traffic signs giving the distance to the next place to stop in an emergency, so you will almost always be able to see a sign. Typically, these will be between approximately 330 and 440 yards apart.”. The DfT could have said “Typically, these will be between approximately 300 and 400 metres apart.”. Why has the DfT decided to yards instead of round numbers of metres?

The use of yards is inconsistent with the emergency marker system. In the emergency marker system, marker posts are placed 100 metres apart and driver location signs 500 metres apart. Both display the number of kilometres from a reference point to help the emergency services to locate stranded drivers. However, only numbers are shown on them. No unit names, abbreviations or symbols are shown to tell drivers what units they are. The emergency marker system exists to benefit drivers but widespread ignorance about this system is probably because they are incompatible with official road signs.

There is another measure to “review existing emergency areas where the width is less than the current 15 foot wide standard. If feasible and appropriate we will widen to this standard.”. This statement obscures the fact that all road features are designed and built exclusively in metric units in accordance with DfT’s exclusively metric specifications to road contractors in the Traffic Signs Manual. Imperial units are only mentioned in the TSM to tell road contractors to put imperial units on road signs for general road users.

I have no doubt that when the DfT updates the Traffic Signs Manual, it will give road contractors the specifications for all these smart motorway features exclusively in metric units with no imperial conversions. The units used in the smart motorway safety measures add more inconsistency and muddle. Once again, it shows the DfT wearing an external imperial mask over an internal hidden metric face. Rip off the mask and it’s all metric underneath. I suspect the mask is just for show. Why do they do this?

12 thoughts on “Inconsistent motorway emergency features”

  1. GB is supposed to be out of the European mess of units, and should see more of the imperial units returning. While most things are packed and sold in metric, (this is only down to the comon market that we joined) we still buy and talk in imperial which we all understand, no confusion!


  2. The Secretary of State is consistent in so far that his speech is in line with the present signage. It is the signage that needs to change. When it eventually does, many things will change with it.

    Liked by 1 person

  3. Imperialyes wrote: ‘GB is supposed to be out of the European mess of units?
    Can you please provide evidence of a European mess of units? The only evidence I’ve seen is due to globalisation and the UK and US markets, namely TV and computer screen sizes given in ‘inches’ in addition to centimetres. Probably save the manufacturers designing and making different packaging for different markets. Car tyres are sometimes shown as an imperial number too, a size, but they are not made to ‘inch’ standards, nor are pipes where threads may show an old imperial-based number. I can assure you that Europe is metric through and through.
    As far as being out is concerned, the UK (not just GB) still has its main trading partners in continental Europe, and will continue using metric in trade. No one in their right mind would think of replacing manufacturing equipment with imperial-based sizes. You wouldn’t be able to export anything. The sizes shown on British packs and jars are still a mix of round metric values and soft conversions to non-rounded values such as 454 g. But they are metric values. The mess in that field is actually extensive and quite confusing.
    So I can assure the only country in Europe where there is genuinely a mess is sadly the UK, where metric has been taught in school as the primary system of measurement for nigh on half a century but teaching is undermined by the continued presence of road signs in imperial units and by rogue market traders.


  4. Wow! Imperialsys is so wrong on everything. The only mess of units has been the historical use of units that imperial is a part of. Imperial units WILL NOT be returning, all that was ever promised was to make it legal to advertise in pounds, but the actual sale will continue in kilograms. No laws are being changed to allow it and no company is going to make pound scales that only suit a small Luddite market of decreasing followers.
    It is not possible to buy imperial when all of the behind the scene filling of packages is rounded metric and even if you ask for imperial, you are getting metric. The machinery can’t fill an imperial amount. Machinery is designed and engineered to do 5 g or 5 ml increments and no imperial amount is equal to a 5 g or 5 mL increment. Whose to say who is confused and who isn’t? More are than will admit to be.

    Liked by 1 person

  5. Imperialyes wrote: ‘GB is supposed to be out of the European mess of units?
    Or put another way, we are/were supposed to be world leaders. If that is world leaders in mess and confusion then we do indeed excel.
    The country gets worse by the day. So, why 220 yards and not a much neater 1 furlong? 3/4 of a mile a nice neat 6 furlongs.
    If there was ever one thing I detested in my driving life was trying to decipher fractions at speed.


  6. So, @imperialyes claims that all UK residents speak only Imperial, eh?
    What about the bloke in this clip, then?
    Seems like a younger totally British chap who appears to be quite comfortable with metric (see what he says near the end of the clip). Too bad he is using an “unnatural” unit of measure according to @imperialyes. Should he be deported for behaving in an un-British way? Maybe the Home Secretary would like to weigh in that! :-0


  7. Ezra, Yes, I have also seen a number of news reports where younger people despite the signs on the roads being in yards spoke in metres of the distance they were from some event. Imperialsys obviously must not be a part of the generation educated in metric and even if that is true after 50 years, there is no reason he couldn’t learn metric on his own and forget FFU as I’m sure many have.
    It isn’t only the education and the signs that determine what units you use, it is the industry you work in. Working in a factory, in a medical facility, as an engineer, in the weather office, operating a deli scale, etc, one is constantly exposed to metric and metric becomes the norm. Very few if any profitable companies use FFU and those that work in them are exposed to metric daily and metric units become the norm in their lives.
    Businesses know metric is the present and future and would never support a return to FFU despite the fake news networks proclaiming it every few months. I’m sure that even Vivian Linacre who was told on his death bed that England would be returning to FFU knew as he breathed his last breath it wasn’t gong to happen and in promising the unlikely event was a mockery to them and their cause.


  8. @Daniel
    Yes, the world really has shifted towards metric compared to at the end of World War II. Think of all the current and former Commonwealth countries that have converted to metric either totally or at least partially and where even Liberia and Myanmar (Burma) and moving towards metric.
    Now if only we can get the USA to start converting, that would finish things off completely (including for the UK!).


  9. Daniel, Many years ago a freind of my wife told me that she would quite happily weigh out 100 g of sodium chloride in the laboratory where she worked, but if she had to weigh out 100 g of salt (or flour) for a recipe at home, she got confused.


  10. Wow Martin, that is scary. But, maybe the difference is the method of weighing. In a lab you use a precision digital balance with taring capability and at home you would most likely have an analogue scale that you have to do a manual calculation. Even in this case though, an effort has to be put forth.


  11. @Daniel/Martin
    This obscure phenomena runs deep in our society.
    Giving a babies mass in kg sends people into some sort of fit, yet buying a 2 kg of potatoes or meat is a normal practice. I do wonder in this instance if it is the mental thought of babies being weighed the same as meat, but it runs much deeper than that.
    The whole country is a mess, led probably by DfT as the most visible to all, but well supported by the media and even more regrettably by various health organisations including the NHS.


  12. Going back to the motorways, it’s just ludicrous that the large blue signs that are intended to help locate broken down motorists and the marker posts that show drivers where the nearest emergency phone is are exclusively metric yet if there is an incident in a tunnel the signs to the emergency exits give distances in yards.

    It’s very telling that signs erected on private land such as height limits at petrol stations are often exclusively metric, for the simple reason that health and safety laws actually require it. Clearly health and safety are not considered quite as important on public highways.


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